Twitter identified 3,814 accounts linked to the IRA, but a similar list was not released for the archived Vine accounts. It wasn’t until CNN, acting on a tip from a Twitter user, contacted Twitter about the accounts were they deleted.

By then, of course, the damage had already been done. Russian-backed Vine accounts had already been viewed and looped millions of times.

Even after CNN alerted Twitter to the problem, two Russian-backed accounts, @GUNS4LIFE and @PoliceState remained live as of Wednesday morning. Each account was linked to suspended IRA Twitter accounts and had posted hundreds of videos featuring false or intentionally divisive content, the news outlet reported. Both accounts published more than 600 videos.

While Twitter suspended the accounts after being alerted to their presence, some are saying that the company isn’t doing enough to monitor content on its platforms.

Sen. Mark Warner (D-Va.), the ranking Democrat on the Senate Intelligence Committee, said Twitter shouldn’t “wait” for Congress to tell them which accounts to delete. “The company needs to take responsibility and be proactive about stopping Russians and other bad actors who are abusing its platform,” Warner told CNN in a statement.

Ellen Ioanes is the FOIA reporter at the Daily Dot, where she covers U.S. politics. She is a graduate of Columbia Journalism School, and her work has appeared in the Guardian, the Center for Public Integrity, HuffPost India, and more.